In U.S. Pat. No. 5,077,908, an apparatus for measuring the roundness of a surface of an object is disclosed. The apparatus comprises a bifurcated head rotatably mounted upon a spring loaded arm. The head has two edge plates which can be brought into tangential contact with the periphery of a rotating object. When the head is brought into contact with objects of different diameters, the points of contact with the edge plates progress along location locus lines which, when produced, intersect an apex. A displacement transducer mounted upon the head has a spring loaded plunger with a probe which is contacted to and detects inaccuracies upon the periphery of the object. The apparatus disclosed in U.S. Pat. No. 5,077,908 is limited to measuring surface roundness.
In U.S. Pat. No. 4,084,324, a surface measurement apparatus is disclosed. It is of the type in which a sensor is traversed along a path in contact with or adjacent the surface of a component under test. The sensor has three or more transducers which, in the described embodiment, physically contact the surface under test and produce individual signals as they are traversed along the same path over the surface of the component under test. The signals produced by the transducers are amplified and combined in such a way that the composite signal, so produced, is not dependent on any variation in the position of the body of the transducers as the device is traversed along the surface of the component under test. Thus, sensors which are not mounted on accurately preformed datum-determining mounts such as a flat bed or an accurate spindle are used. The apparatus disclosed in U.S. Pat. No. 4,084,324 is limited to measuring surfaces.
In U.S. Pat. No. 4,048,849, a method and apparatus for measuring surface flatness of a material is disclosed. A set of three non-contact gap detectors are arranged at predetermined regular intervals parallel to and in the direction of measurement of the surface flatness of a material. The gap between the material and each detector is measured and computed continuously to continuously measure and indicate the surface flatness of the material without being affected by an overall curve of the material. Also, the period of the occurrences of the defect in the flatness of the material is measured. The apparatus disclosed in U.S. Pat. No. 4,048,849 is limited to measuring the surface flatness.
In U.S. Pat. No. 5,022,267 a roller gauge is disclosed that comprises means for rotating a roller, mechanical-to-electrical transducer means for measuring the diametric variation around the circumference of the roller and converting the diametric variations of the roller into electrical signals which are a function of the diametric variation; and an electrical signal conversion system and a weighting circuit. The apparatus disclosed in U.S. Pat. No. 5,022,267 is limited to measuring the diametric variation surface of a roller.
In U.S. Pat. No. 4,625,429, an apparatus for checking the roundness of rotating objects is disclosed. The apparatus for checking the roundness of objects comprises a basement supporting a motorized spindle for rotating the object to be checked about a horizontal axis, a stanchion fixed to the basement, a control lever and a support element rotatably coupled to the stanchion for rotation about relevant horizontal axes, a measuring device coupled to the lever and the support element, and a processing device. The measuring device comprises a member vertically suspended to the lever and rotatably coupled to the support element, a Vee device fixed to the member and adapted to be arranged upon the object and two measuring heads with movable feelers adapted to contact diametrically opposed points of the object. The processing device is connected to the measuring heads for providing measurements of the out-of-roundness and of the diameter of the object. The apparatus disclosed in U.S. Pat. No. 4,625,429 is limited to measuring the surface roundness.
In U.S. Pat. No. 6,272,762, an ovality measurement tool is disclosed. It measures ovality of a circumferentially deformable cylindrical element having a cylindrical element support, a sensing element for traversing the circumference of the cylindrical element, the sensing element is movable radially with respect to the cylindrical element, and a readout device for reading the amount of movement of the sensing element as it traverses the circumference of the cylindrical element. The apparatus disclosed in U.S. Pat. No. 6,272,762 is limited to measuring the surface ovality.
In EP 1 043 564 A2, a machine control gage system having a control unit, which analyzes roundness of a workpiece, is disclosed. The control unit controls a grinding machine controller in such a manner as to machine the workpiece to a desired size according to data measured by a measuring head. The control unit analyzes roundness of the workpiece according to the data measured by the measuring head and displays the roundness on a touch panel. The invention disclosed in EP 1 043 564 A2 is limited to only indicating roundness of a work piece.